1. Field of the Invention
The present invention relates to vacuum cleaners for removing burned materials, including even still hot materials, out of a fireplace or stove, and particularly to flame retardant filter systems for such vacuum cleaners.
2. Prior Art
Removal of ashes and unburned materials from wood burning fireplaces and stoves is often a difficult and messy task for users of such devices. Particularly should live coals be present in such removed materials that can cause damage to conventional vacuum cleaners, and may even constitute a fire hazard. An earlier ash vacuum adapter of the present inventors, U.S. Pat. No. 4,868,949, shows a canister arrangement for connection to a vacuum source for drawing ashes and coals into a canister. Which arrangement employs a filter formed of a fire retardant material and provides a rod for shaking which filter from without the canister. Distinct from this earlier adapter, the present invention includes an integral vacuum source and provides a duel inner and outer filter system that includes an open frame for supporting the outer filter element. Which invention also provides a rod arrangement connected to the open frame and extending beyond the canister for shaking that frame from without the unit, dislodging materials collected on both the inner and outer filters that fall therefrom.
Functionally similar to the adapter device of U.S. Pat. No. 4,868,949, patents to Rasmussen, U.S. Pat. No 4,476,608, and Natale, U.S. Pat. No. 4,613,345, shown devices for connection to a vacuum source for pulling dust, ashes, or like materials, therein and involve filter arrangements. Unlike the present invention, however, the Rasmussen Patent shows only a divider wall for filtering heavy particles out of an air flow, and the Natale patent shows a disposable filter element. Additionally, a United Kingdom Patent to Ruau, No. 294,501, shows a filter element for connection to a vacuum source wherein a single filter element is maintained around a spring structure with a bottom plate connected to a shaker rod. The manual movement of which rod is to shake off materials collected on that filter surface. Which Ruau patent, however, does not include a self contained vacuum source, nor does it involve a pair of inner and outer filter elements separated by a box frame filter element retainer of the present invention.
Heretofore, a number of canister suction or vacuum type cleaners have been developed, with some suitable for ash collection. For example, an early canister vacuum, identified as a dust separator, is shown in a patent to Bieth, U.S. Pat. No. 1,946,665, that provides a baffle arrangement for separating particles out of an air flow. A patent to Bryan, U.S. Pat. No. 3,910,781, also shows a vertical or canister type vacuum cleaner with an internal, dust separating filter, which filter, however, appears to be rigidly maintained as an upright cone, and does not include structure for shaking materials therefrom. A canister type suction cleaner is also shown in a patent to Gongwer, U.S. Pat. No. 4,355,434, that is arranged for ash removal, as from a fireplace, and includes both a baffle structure as well as a filter, but does not involve a flexible outer filter that can be shaken from without the device.
Like the above cited Gongwer patent, patents to Raminger, U.S. Pat. No. 2,531,920, and Reid, U.S. Pat. No. 4,342,131, show vacuum cleaners for removal of ashes and unburned materials from fireplaces and stoves. Neither of these cleaners, however, employs a filter system and an arrangement for shaking an outer filter element thereof like that of the present invention. Another cleaner devices that is also intended for cleaning fireplaces, but does not include a filter structure and shaking arrangement like that of the present invention, is shown in a patent to Fullenwider, U.S. Pat. No. 4,363,674.